Therm-a-Rest has quit making the Trekker Lounge, but you can check out our current lineup of backpacking chairs here.
The Therm-a-Rest Trekker Lounge chair ads extended leg comfort to the Therm-a-rest Trekker Chair (that we did a full hands on review of). For the extra comfort, you add on a few ounces of weight and about $10. The Trekker Chair will work with a shorter (50-60") sleeping pad. The Trekker Lounge really only works with a full size (72-78") sleeping pad that is rectangular. It does not work as well with the more tear-drop shape of a pad like the Therm-A-Rest ProLite Plus.
Once nice benefit of the Trekker Lounge is that it ads some protection to the bottom of your pad. The regular Trekker and even smaller Therm-a-Rest Compack offer much less protection to the bottom of your pad when sleeping or using it as a chair.
Make sure you measure your sleeping pad before you buy this pad. It comes in two sizes: 20 x 72 inches or 25 x 78 inches.
This Therm-a-Rest Trekker Lounge a more comfortable version of their lighter weight Therm-a-Rest Compack Chair. The Compack is ideal for backpackers that value weight savings over comfort. The Compack weighs 7.0 oz in the 20" wide version — it's 11 oz lighter than the Trekker Lounge Chair. The Comapck is also designed to work better with lighter Therm-a-rest sleeping pads that have a more tear-drop shape like the Therm-A-Rest ProLite.